[HECnet] Reading RT11 files under Windows or Linux

[Johnny Billquist]

On 2021-04-22 16:53, Robert Armstrong wrote:
>> Dave McGuire <mcguire at neurotica.com> wrote:
>>   On the 780 it's just microcode patches, on the 730 it's all of
>> microcode. (both as far as I can recall)
> 
>    Dave's right - ALL the 730 microstore, including the code for the IDC and/or FPA if you have them, is RAM.   From power on a 730 takes about 15 minutes before it's even ready to boot VMS; that's a consequence of loading all that code from a fairly slow TU58.  Don't know how long it takes an 8600, but at least it has the benefit of an RL02 for the console media.

It takes a minute or two before the 86x0 is all ready and starting VMB.

>    Most (I won't say "all"!) of the other VAXes had at least some chunk of the microstore in ROM.  Most of them had some sort of microcode patch mechanism that allowed chunks of microcode to be loaded into RAM at power up time, but this was just a fraction of the total microcode.

I think that apart from the 730 and the 86x0 then, I'd say all had most 
of the microcode in ROM or flash, and then some way to patch it.

But of course, I bet someone will remember the next exception. :-)

>    Idle curiosity makes me wonder about the V11/KA820-825 now.  IT was like the 750 in that the console functions were implemented in microcode (i.e. no front end) but it did have console media in the form of an RX50.  Can't remember if it actually loaded some microcode patches from the diskette, like the 750 did with the TU58, or if all the V11 microcode was permanently buried in the chip.

The 750 could definitely have the patch on the TU58, but that wasn't how 
it usually was handled. Distribution was on TU58, but you normally 
copied that over to the actual system, and it got patched from there. 
Otherwise it would be slow and complex if you wanted to boot some or 
other OS at power up. The boot selector switch only tells which device 
(1 out of 4) it boots from, and unless you select TU58, it won't boot, 
or suck anything in from there.

Fun fact: NetBSD still ships with the microcode patches for the 
VAX-11/750, and applies them if necessary.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
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